Examples of a technique relating to a balance circuit provided in a power storage device are disclosed in, for example, PTLs (Patent Literatures) described below.
PTL 1 described below discloses a power storage device in which a balance circuit of a passive balance type including a resistor, and a temperature sensor are provided for each of a plurality of electricity storage elements (battery cells). PTL 1 also discloses a technique of controlling an ON/OFF state of a switch of each balance circuit in such a way that a temperature of the resistor detected by the temperature sensor is maintained at a maximum use temperature during an operation of each balance circuit.
In addition, PTL 2 described below discloses a power storage device that includes an assembled battery constituted of a plurality of series-connected cells, and a cell controller controlling a balance operation of each cell. The cell controller repeats an intermittent operation of cells by selecting one or a plurality of cells having a voltage value equal to or more than a cell capacity adjustment target voltage, and connecting an intermittent operation unit to the selected cell or cells. Accordingly, residual capacity fluctuation among the cells is reduced.
In addition, PTL 3 described below discloses a technique of adjusting charge amounts of a plurality of series-connected battery cells by using a cell balance circuit including a resistive element. In particular, PTL 3 discloses a technique in which a battery cell having a higher temperature is connected to the cell balance circuit for a longer period of time and a discharge amount during a balance operation is increased.
In addition, PTL 4 described below discloses a technique in which hysteresis is given to a threshold voltage for use in turning ON/OFF of charge current in order to avoid an unstable charge operation that may be caused by bypassing a power storage unit reaching a charge target voltage in charging of a plurality of series-connected electricity storage units.
In addition, PTL 5 described below discloses a technique in which surplus electric power is regenerated to another cell by using an equalization converter when a charge state of a certain single cell in a battery pack is greater than a target charge state.